You can now jailbreak tvOS 11 to 11.1 on Apple TV 4 and Apple TV 4K using LiberTV 1.1 (aka LiberTV11) release. Here are the details.
LiberTV 1.1 jailbreak for tvOS 11 / 11.1 on Apple TV 4 and Apple TV 4K to arrive really soon with jailbreak toolkit for iOS 11.1.2 to follow shortly after.